Cidara posts data from head-to-head trial against Merck antifungal

Silver stain showing Candida psuedohyphae and budding yeast forms (Pulmonary Pathology/CC BY-SA 2.0)

A phase 2 trial of Cidara Therapeutics’ antifungal prospect rezafungin has met its objectives. The trial found the drug performed numerically better than Merck’s Cancidas, offering Cidara encouragement as it heads toward phase 3 data.

Cidara wrapped up the first part of the phase 2 study last year but moved straight into a second part to ensure it had data on enough patients to satisfy regulatory safety requirements. The second part of the trial compared rezafungin to Cancidas in 91 patients with invasive Candida infections. Part way through the study, Cidara changed the dosing regimen to align it with the phase 3 study.

Now, Cidara has shared data from the second part of the phase 2 trial. The study wasn’t powered to show statistically significant differences or non-inferiority between the arms, making it impossible to draw concrete conclusions. But Cidara found cause for encouragement in the numbers.

Of the 46 patients treated with the phase 3 regimen across both parts of the phase 2 trial, 37 had achieved clinical cure after 14 days. Forty-three out of the 61 patients in the pooled Cancidas cohort achieved clinical cure at that time point, resulting in the success rate in the rezafungin arm coming in 10 percentage points above that of Merck’s comparator.

Results from patients treated in the second part of the phase 2 contributed to rezafungin numerically outperforming Cancidas, but the sample size is small. With Cidara switching to the phase 3 regimen mid-study, only 15 subjects were treated with that dose in the second part of the trial. 

That limits the value of the data in isolation, but the results nonetheless add to understanding of the effects of rezafungin.

“The positive outcomes from Part B of the STRIVE trial, which are similar to those from Part A, further substantiate the potential efficacy and safety of rezafungin in extremely ill patients affected by fungal disease,” George Thompson, an associate professor at University of California, Davis, said in a statement. 

Shares in Cidara increased by more than 10% in premarket trading, but that still left the stock below $2.